1. Field: The field of the invention is manual tools, particularly socket wrenches wherein differently sized heads are designed to interfit together.
2. State of the Art: Typically, socket wrench sets include a number of socket heads sized for a range of nuts and bolt heads. The socket heads are used interchangeably with a single wrench handle. Such socket sets are difficult to store and transport between use sites, a specially designed case typically being necessary. When the nut or bolt head is in a recessed location, the socket must be engaged by an extension drive bar in turn engaged by the handle at its opposite end. U.S. Pat. No. 1,371,350 discloses a socket set which further utilizes such a drive bar as a carrier for the wrench set between uses. The individual sockets do not, however, engage together for use U.S. Pat. No. 851,068 discloses a set of socket heads which to a limited extent can be used while assembled together. The sockets in this set assemble in order of increasing size from a drive handle. To use one of the smaller sockets, all of the larger sockets must be removed from the set. More recently, U.S. Pat. No. 4,620,460 also discloses a set of socket heads designed to fit together to be used as an extension. The socket heads cannot be assembled in random order, but only in order of decreasing size from the handle. Each socket of the desired size may be removed from the stack and secured at the end to the smallest socket in the set. This set is inconvenient to use as an extension substitute, because the general order of the sockets must always be preserved, and the particular smallest socket always used. Another problem not solved by the prior art is the removal of nuts through which the bolts extend a substantial distance. The interior cavities of state of the art socket heads are too shallow to engage such nuts, except in specialized, long shank spark plug tools or the like. Thus, prior art socket head sets fail to provide the versatility and adaptability needed to accomplish frequently required tasks with a minimum of inconvenience.